Numerous studies have reported beta-hydroxynitrosamines, as well as their oxo derivatives to be metabolites of nitrosamines in vivo and in vitro. Beta-hydroxy-nitrosamines are and can be produced in the environment from a wide variety of ubiquitous beta-hydroxyamines. This laboratory has shown that these beta-oxidized nitrosamines fragment and/or are transformed into a number of other nitrosamines when treated with base and that the fragmentation rate is highly dependent on the syn/anti stereochemical arrangement of the N-nitroso function. Here we propose to elucidate further the catalytic and structural features which effect these transformations and in particular to examine the effect of the N-NO stereochemistry on various aspects of nitrosamine carcinogenesis. We also propose to elucidate the processes by which nitrosenamines are formed from beta-oxidized nitrosamines as well as how these unsaturated nitrosamines behave toward environmentally and biologically prevalent nucleophiles. These studies are of particular importance to an understanding of the health hazards posed by diethanolnitrosamine and N-nitrosomorpholine which are environmentally ubiquitous nitrosamines. Considerable work is proposed to seek an answer to the question "Is there a biochemical retroaldol fragmentation of beta-oxidized nitrosamines?" The use of 13C labeled substrates and 13C NMR is proposed to aid in answering this question. Tests of various hypotheses relating to the role of beta-oxidized nitrosamines in nitrosamine carcinogenesis are proposed. The exploration of the fragmentation of beta-oxidized nitrosamines via 1 electron redox pathways involving the fission of the N-N bond is proposed. The use of the Ames mutagen assay to further our understanding of various biochemical transformations is proposed.